This relates to a flexible support for a thin electrically conductive electrosurgical electrode. More particularly, a circumferential frame shaped to capture an edge of the electrosurgical electrode.
U.S. Pat. No. 5,277,201 has a balloon with electrodes to delivery radio frequency energy attached to the balloon for treatment of the endometrium.
U.S. Pat. No. 5,443,470 has a regulated heating device with a balloon having electrodes for delivery of radio frequency energy to the endometrium.
U.S. Pat. No. 5,562,720 has a method of making a balloon with electrodes attached thereto including use of sheet or curing a coating on a mandrel to form the balloon to carry electrodes or sensors.
The method of manufacture for the expandable balloon includes casting silicone elastomer dispersion over the radio frequency electrodes and-allowing the dispersion to remain volatile for an extended period of time before curing and completing the balloon assembly. The casting process embeds the electrodes in a consistent wall thickness of elastomer. The electrosurgical electrodes are not well captured by the balloon during inflation of the electrode containing balloon within the uterus. The casting process also produces a minimum wall thickness of the elastomer which may be too thick and makes the balloon bulky when it is folded down and placed into the delivery sheath of the device. As a result, product yields have been low due to electrode dislocation on the balloon surface during fold down into the sheath. Average production throughput times are estimated in days to complete the balloon casting and assembly.
U.S. Pat. No. 4,955,377 has a balloon with an electrode there inside which heats therethrough.
A flexible support for a thin electrically conductive electrosurgical electrode includes an edge therearound defining its shape about its major surfaces. One or more circumferential frames each shaped to capture the edge of the electrosurgical electrode are preferably on the support. An under cut is most preferably on the circumferential frame for substantially holding and enclosing the edge of the electrosurgical electrode. A membrane may be integral with the one or more circumferential frames. The membrane can extend from each circumferential frame and might be coextensive with each circumferential frame. It is preferred that the membrane has a thinness sufficient to allow expansion in deference to the one or more circumferential frames. The one or more circumferential frames, the under cut and the membrane made in the preferred embodiment of the flexible support be made from a flexible polymer.
The flexible polymer of the preferred embodiment has a percent of elongation in the range of 500% to 1500%. The one or more circumferential frames and the integral membrane form most preferably an inflatable balloon with an interior surface and an exterior surface with an inflation port therethrough. The under cut on the one or more circumferential frames may be situated, placed or disposed for substantially holding and enclosing the edge of each electrosurgical electrode on the exterior surface of the balloon. The membrane may expand upon ainflation of the inflatable balloon. The one or more circumferential frames can include a window opening to a recess peripherally surrounded by the under cut and a wall within the under cut is disposed to most preferably abut the edge of electrosurgical electrode, the window opening shaped as the major surface of the electrosurgical electrode while sized slightly smaller to define the under cut. The flexible polymer is in the preferred embodiment an elastomeric material having a high dielectric. The flexible polymer is most preferably a silicone with a temperature resistance of at least 100 degrees centigrade. An adhesive can be if desired applied to bond one major surface of the electrosurgical electrode within the circumferential frame.
The membrane is desired to be integral with the one or more circumferential frames, the membrane resides within the circumferential frame and forms the exterior surface of a balloon.
A method of making a flexible support for a thin electrically conductive electrosurgical electrode may have steps. Providing a mold cavity to receive and shape the flexible support is a preferred step. The mold most preferably has an unpolished surface finish to enhance release properties during removal of the flexible support. A step could include filling the mold cavity with a thermosetting polymer. The step of heating the mold cavity to a temperature sufficient to cure the thermosetting polymer into one or more circumferential frames each shaped to capture the edge of the electrosurgical electrode might follow. An under cut on the circumferential frame most preferably is for substantially holding and enclosing the edge of the electrosurgical electrode. A membrane is desired to be integral with the one or more circumferential frames for extending from each circumferential frame and coextensive with each circumferential frame. The membrane. may have a thinness sufficient to allow expansion in deference to the one or more circumferential frames. The one or more circumferential frames, the under cut and the membrane could in a step of the preferred method be made from the thermosetting polymer. The steps of folding the flexible support and sealing the abutting sides thereof to form a balloon can be performed if the molding is of a flat preform. The step of inserting a core into the mold cavity to form a balloon during the step of filling may be an alternate step.
A mold for making a flexible support balloon for a thin electrically conductive electrosurgical electrode with an edge therearound defining its shape about its major surface is preferred. Top and bottom platens may be movably supported to fit together for the preferred mold. The top and bottom platens can therein define a mold cavity when they are fit together. A mold cavity is preferably disposed in either the top platen or bottom platen. A pedestal is located preferably upstanding within the mold cavity. It is desired that a plate in the preferred mold be mounted atop the pedestal.
The flexible support is part of an ablation device for delivering necrosis to the endometrium to eliminate uterine bleeding. The flexible support is preferably in the shape of an expandable balloon carrying electrosurgical electrodes to deliver radio frequency energy to the endometrial tissue thereby causing necrosis to the endometrium.
To overcome the difficulties of previous methods and designs, an apparatus design and method of manufacture and equipment therefor have been created to address the issues with existing balloons. The new design consists of a method for molding the balloon with specific molded locations -for the electrosurgical electrodes. These molded locations include an under cut to capture the edge of the electrosurgical electrode. The molded balloon includes a membrane between the electrode locations. The membrane preferably has a thinner wall section. This difference in wall section allows the balloon to expand within the uterus more uniformly without dislocating the electrosurgical electrodes from the balloon surface. Thus the uterine space is filled more uniformly for distributing the electrosurgical electrodes and subsequently radio frequency energy to more uniformly within the uterine space. This design and method of manufacture also eliminates the inconsistencies of the casting method by molding a uniform, consistent geometry with varying yet controlled wall thickness. The molding process also allows for a thinner balloon wall thickness which is desirable for fold down of the balloon into the device sheath without electrode dislocation form the balloon surface. This thinner wall section allows for a smaller device sheath diameter which is also desirable for insertion and deployment of the balloon into the uterus.